Find longest substring without repeating characters
Company: TikTok
Role: Machine Learning Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Onsite
## Problem
Given a string `s`, find the length of the longest **contiguous substring** that contains **no repeated characters**.
### Input
- A string `s` (may contain letters, digits, symbols, and spaces).
### Output
- An integer: the maximum length among all substrings of `s` that have all unique characters.
### Examples
1. `s = "abcabcbb"` → output `3` (e.g., "abc")
2. `s = "bbbbb"` → output `1` (e.g., "b")
3. `s = "pwwkew"` → output `3` (e.g., "wke")
### Constraints (typical interview assumptions)
- `0 ≤ len(s) ≤ 10^5`
- Aim for an algorithm faster than `O(n^2)`.
### Notes
- Substring must be contiguous (not a subsequence).
Quick Answer: This question evaluates proficiency in string processing, duplicate-detection using appropriate data structures, and algorithmic complexity analysis within the Coding & Algorithms domain.
Return the length of the longest contiguous substring with all unique characters.
Constraints
- Inputs are Python literals matching the function signature.
- Return a deterministic exact-match value.
Examples
Input: ('abcabcbb',)
Expected Output: 3
Explanation: Prompt example 1.
Input: ('bbbbb',)
Expected Output: 1
Explanation: Prompt example 2.
Input: ('pwwkew',)
Expected Output: 3
Explanation: Prompt example 3.
Input: ('',)
Expected Output: 0
Explanation: Empty string.
Hints
- Model object-style prompts as operation streams when needed.
- Handle empty and boundary cases before the main logic.